press the 7, 9 and power keys simultaneously to enter the system mode, then power off and press 1, 7 and power key simultaneously to enter the kernel mode which provides the following services:

    program download to download user program. the download procedure is same as download program in system mode. please refer to the above section.

    update kernel to update system kernel. sometimes the kernel might be changed for improving performance or other reasons. this function allows you to keep the kernel updated. the update procedure is same as download user program, but note that after updating the kernel, please do not power off until the system restart itself.

    test & calibrate to perform a burn-in test and fine tuning the system clock. this function is for manufacture purpose only.